PHY1 Core Assesment Lab
F = ma
Objectives:
(1) To determine the mass of the cart without using a balance.
(2) To discribe an experiment to the students and to have them
(a) Design the experiment
(b) Collect data
(c) Do appropriate calculations
(d) Write a short report
Materials:
A wodden cart with wheels, string, 50 g mass hangers, 50 g, 100 g and
200 g masses, 2.0 cm wide index cards taped to side of cart, a photogate
timer or stopwatches, wheels attached to a clamp, and meter stick.
Setup:
See the following diagram.
Fg
Procedure:
The system is defined as the cart, weights and hanger, since these are the
objects that are accelerating. The total mass of the system must remain
constant. The applied force on the cart is determined by the weight (Fg) of
the hanging mass. A plot of F-ma for a series of data points where the
applied force is plotted on the y-axis and the acceleration of the system is
plotted on the x-axis. The slope of this plot, will be the mass of the
system. Data points are collected by transferring mass from the cart to the
hanger. The accleration can be determined in one of two ways:
(a) Using a stopwatch, measure the time needed to accelerate the system
some measured distance. d = 1/2at2
(b) Use the photogate to measure the final velocity at the end of a
measured distance. The photogate measures the time the index card
blocks the IR beam. Vf = d/t and Vf2 = Vi2 + 2ad
PHY1 Core Assesment Lab
F = ma
Report Format: The report will not exceed a total of two pages, using single spaced 12
point “times” font. The following section headings must be included.
Name:
Title:
Purpose:
Materials:
Procedure:
Data and Calculations:
Conclusions:
Grading Rubric
Item
Title and
Purpose
Criteria
•
•
•
Report
•
Presentation •
•
•
Equipment •
•
•
Data
•
•
Calculations •
•
Graph
•
•
•
Conclusions •
•
Brief appropriate
descriptive title
Clear statement of
purpose
3rd person passive
Spelling and grammer
Clear and concise
Sections headings
List of equipment
Correct names
Diagram of set up
An organized table of
measured data
including descriptive
headings and units
Sample calculations
Correct mathematics
Correct use of
equations and
variables
Graph with axes labels
and units
Appropriate variables
on the x and y axes
Best fit line and slope
calculations
Brief explanation of
experiment approach
Statement of result
Identifcation of
sources of error
Expert
(3 pts)
Skilled
(2 pts)
Novice
(1 pts)
Deficient
(0 pts)
PHY1 Core Assesment Lab
F = ma